超声振动辅助金属箔板微冲裁成形机理与断面质量控制

Micro foil part is one of key components used in inertial navigation system. This kind of parts are fabricated with the blanking and machining process. The manufacture efficiency and qualified rate of parts are both very low, which restricts the improvement of inertial accuracy. Then, the ultrasonic vibration assisted micro foil blanking process is carried out as a kind of new process in the project. For the Blaha effects and surface effects in the ultrasonic vibration plastic deformation, the crack initiation and propagation is restricted, and the properties of plastic deformation could be improved, and the friction at contact surface becomes lower. Then, the quality of micro blanking is raised. We will study the plastic deformation and fracture behaviors of metal foils under ultrasonic vibration. Based on the crystal plasticity theory and principle of superimposed stresses, the constitutive model of metal foil will be established under ultrasonic vibration. The shear deformation in micro foil blanking will be investigated on the condition of multiple constraints. The size effects of shear deformation in micro blanking and mechanism of crack initiation and propagation will be analyzed. And the tribological behaviors under ultrasonic vibration will be studied. The process for control of cross section quality will be explored. The investigation of ultrasonic vibration assisted micro blanking process will be carried out to reveal its mechanism. Finally, the micro foil parts with high quality will be accurately formed at only one time. It will promote the wide application of microparts in practical production, which has important practical value and scientific significance.

金属箔板微型构件是惯性导航等系统的核心构件之一，目前采用冲裁成形后再切削加工的方法，制造效率和成形件合格率均很低，严重制约了导航精度等系统性能的提高。为此，本项目提出超声振动辅助箔板微冲裁成形新工艺，利用超声振动塑性成形的Blaha效应和表面效应，抑制微冲裁剪切变形中的裂纹萌生与扩展，提升箔板塑性变形均匀性，降低接触摩擦力，以提高微冲裁成形质量。开展超声振动金属箔板塑性变形性能和断裂行为研究，基于晶体塑性理论和应力叠加原理，构建超声振动下箔板材料本构模型；研究多约束作用下箔板微冲裁剪切变形规律，揭示箔板微冲裁剪切变形尺寸效应、裂纹萌生与扩展机理，探讨超声振动下接触摩擦行为，探索箔板微型构件断面质量控制方法；开展超声振动辅助微冲裁成形工艺研究，揭示超声振动辅助金属箔板微冲裁成形机理，实现高质量箔板微型构件的精密一次成形，促进其在实际生产中的广泛应用，具有重要的实用价值和科学意义。

本项目针对惯性导航系统中的金属箔板微型构件制造瓶颈问题，提出了超声振动辅助箔板微冲裁成形新工艺。使用机电转换系数高的PZT-8压电陶瓷夹心式超声换能器，优化设计了超声振子和超声驱动电源，研制了箔板超声振动微拉伸实验装置开展实验研究。结果表明，施加超声振动后，出现了材料流动应力降低的Blaha效应；振幅越大，屈服强度降低越明显；硬化指数增加，表明均匀塑性变形量增加；板厚越小，流动应力降低越大，出现了Blaha效应与尺寸效应的耦合作用；抗拉强度降低，断口中心区域的韧窝数量明显增多。从位错吸收超声振动能量角度，基于晶体塑性理论、考虑超声能量和应力叠加效应构建了材料软化本构模型，开展了超声振动辅助微冲裁过程数值模拟，揭示了超声振动抑制裂纹萌生、提高断面质量的作用机理。. 为了提高能量传递效率，优化设计了振子-冲头一体化的振子，研制了超声振动辅助微冲裁模具开展实验研究。结果表明，施加润滑剂后表面粗糙度从Ra0.101降低到了Ra0.006μm；超声振动使裂纹萌生从厚度的48.1%延缓至59.1%、撕裂带角度从18°减小到9°；EBSD分析表明，晶体取向更集中，小角度取向差比例减小，而大角度差比例增加，说明不利取向晶粒也参与了塑性变形。提出了超声振动-背压微冲裁工艺新方法，开展了导电环、微靶薄壁遮光圆环等微冲裁工艺研究，在超声振动振幅1.66 µm、频率36.1kHz，冲裁速度1mm/s等条件下，冲裁成形的最小特种结构尺寸为0.3mm，尺寸误差最大为2μm，光亮带比例95.32%，毛刺仅为2.93μm，满足了惯导系统、惯性约束聚变微靶系统等微系统的需求。. 发表学术论文9篇，其中M&D等SCI高影响因子期刊论文8篇，申请国家发明专利6项，其中已经授权3项，培养研究生11名，参加国内外学术会议8次，其中邀请报告2次，获得最佳学术报告2次。. 总之，本项目圆满完成了任务书规定的研究内容，实现了研究目标。